Table of contents : 

• most arise from oro-faecal route
• intestinal protozoa and helminths (IPH) : in 1999, > 70% of Cambodian children were infected with intestinal worms. Not only do infected children weigh as much as 4.4 pounds (2 kilograms) less than healthy children, they also have a much higher chance of becoming anemic. If anti-parasite treatment is administered, however, infected children show a dramatic increase in their short-and long-term memory, as well as their reasoning capacity and reading comprehension. School absenteeism drops by as much as 25%. In 2001, the WHO set a target of covering at least 75% of school-aged children with regular treatment as the global goal for parasite control for 2010. According to reports sent in from the > 6500 schools where the campaign took place, > 75% of Cambodia's nearly 3 million school-aged children have now been treated. Intestinal worm infections affect at least 2 billion people worldwide and are a significant public health threat in regions where sanitation and hygiene levels are inadequate.
• enthelaminthes : intestinal heminths
• intestinal geohelminthosis / geohelminthiasis : soil-transmitted helminths, e.g.
• Ascaris lumbricoides
• Ancylostoma doudenale
• Necator americanus
• Trichuris trichiura
helminthemesis : the vomiting or expulsion through the mouth of intestinal worms
Examination of the intestinal epithelial submucosa of mice after primary and secondary infections by a natural gastrointestinal parasite revealed a distinct immune-cell infiltrate after challenge, featuring IL-4–expressing memory CD4⁺ T cells that induced IL-4 receptor^hi (IL-4Rhi) CD206⁺ alternatively activated macrophages. In turn, these alternatively activated macrophages (AAMacs) functioned as important effector cells of the protective memory response contributing to parasite elimination, demonstrating a previously unknown mechanism for host protection against intestinal helminths^ref
• invermination : infestation of the body by vermin
• T_h2 polarization of immune response
• eosinophilia (related to level of tissue spreading ; unmutated if the helminth persists in cysts or lumens)
• mast cells are important for intestinal parasite expulsion and also induce elevated epithelial permeability depending on degradation of the tight-junction protein occludin
• helminthoma : a discrete nodule of granulomatous inflammation (including the healed stage) caused by a helminth or its products, so termed on the basis of certain gross resemblances to a neoplasm
• parasite index : the percentage of individuals in a population whose blood smears show the presence of parasites
• web resources :
• Intestinal parasites at WHO
• Parasitology Section of Microbiology and Immunology On-line
• Parasites and Parasitological Resources

• Cestoda / Cestoidea (tapeworms) : characterized by the absence of a mouth and digestive tract and by the presence of a noncuticular layer covering their bodies.
• hexacanth embryo : the 6-hooked embryo, or onchosphere, characteristic of most tapeworms of humans and domestic animals.
• vitellarium / vitelline gland : an accessory genital gland found in flukes and tapeworms which secretes the yolk and shell for the fertilized egg
• strobila / strobile / strobilus [L., from Gr. strobilos anything twisted up] : the chain of proglottids constituting the bulk of the body of adult tapeworms; considered by some to include the entire body, including the head, neck, and proglottids.
• Cestodaria : unsegmented tapeworms which are endoparasitic in the intestines and coelom of various primitive fishes and rarely in reptiles.
• Eucestoda / Cestoda : the true tapeworms, which have a head or scolex, and segments or proglottides. Adults are endoparasitic in the alimentary tract and associated ducts of various vertebrate hosts; their larval stages (cysticercus, coenurus, hydatid, sparganum) may be found in various organs or tissues.
• Cyclophyllidea : an order of tapeworms comprising 7 families that are habitually or accidentally parasitic in humans and domestic animals
• Davaineidae : a family of small tapeworms of the order Cyclophyllidea, subclass Cestoda, which parasitize mammals and birds.
• Davainea [Casimir Joseph Davaine, French physician, 1812–1882] : a genus of tapeworms of the family Davaineidae. D. proglottina causes severe enteritis in fowls.
• Raillietina[Louis-Joseph Alcide Railliet, French biologist, 1852–1930] : a genus many species of which infect birds, domestic fowl, and mammals.
• Raillietina asiatica
• Raillietina celebensis
• Raillietina demarariensis (Taenia demarariensis)
• Raillietina formosana
• Raillietina loechesalavezi
• Raillietina madagascariensis (Taenia madagascariensis) (the Madagascar tapeworm)
.. have been reported from human infections (raillietiniasis)
• Anoplocephalidae : a family of medium-sized or large tapeworms of the order Cyclophyllidea, subclass Cestoda, commonly parasitic in various herbivorous animals and man. Genera of medical and veterinary importance are
• Anoplocephala : a genus found in horses
• Bertiella
=> bertielliasis
• Bertiella satyri (a.k.a. Bertiella studeri) is found in humanshumans (Beaver PC, Jung RC, Cupp EW. Cyclophyllidean tapeworms. In: Beaver PC, Jung RC, Cupp EW, editors. Clinical parasitology. 9th ed. Philadelphia: Lea and Febiger; 1984. p 505–6) and other primates in India, Africa, the West Indies, the Philippines, and various islands in the Indian Ocean
Epidemiology : > 50 cases of human infection have been recorded. Animal infection has been recorded in some provinces in China, and human bertiellosis has been recorded in Sri Lanka^ref, Saudi Arabia (El-Dib NA, Al-Rufaii A, El-Badry AA, Al-Zoheiry AA, Abd El-Aal AA. Human infection with Bertiella species in Saudi Arabia. Saudi Pharmaceutical Journal. 2004;12:168–9), Vietnam^ref, Japan^ref, India^ref, Thailand, Malaysia, and China^ref.
Transmission : the lifecycle of the cestode requires 2 hosts; nonhuman primates are generally the final host, while oribatid mites are the intermediate host, in which the infective cysticercoid of the cestode develops. Orbatid mites may exist in soil to maintain natural infection, and the definitive host is infected by eating or otherwise coming into contact with contaminated soil or food. Humans are infected by unconsciously swallowing infected mites, and in Mauritius, children were infected by eating guavas that had fallen on the soil^ref. Other human infections may have occurred, but infected persons may have had mild symptoms and not noticed expelling the segments, so local doctors may have considered the cases to have been caused by a common cestode. To prevent human bertiellosis, the relationship between human cases and the natural host must be investigated.
• Bertiella mucronata can infect humans (Beaver PC, Jung RC, Cupp EW. Cyclophyllidean tapeworms. In: Beaver PC, Jung RC, Cupp EW, editors. Clinical parasitology. 9th ed. Philadelphia: Lea and Febiger; 1984. p 505–6)
• Moniezia
• Paranoplocephala
• Thysanosoma : genus of cestodes of the family Anoplocephalidae.
• Thysanosoma actinoides, the fringed tapeworm, is found in the bile ducts and small intestines of sheep, cattle, deer, and antelope in the western United States and in Africa.
• Linstowiidae : a family of medium-sized or small tapeworms which parasitize birds, reptiles, and mammals, including humans; medically important genera are
• Oochoristica : a large genus of tapeworms which are parasitic in birds, reptiles, and mammals
• Inermicapsifer : some are parasitic in hyraxes and rodents in Africa.
• Inermicapsifer arvicanthidis has been found in humans in Cuba and Central America.
• Mesocestoididae : a family of medium-sized to large tapeworms which parasitize carnivorous birds and mammals.
• Mesocestoides is the type genus, whose larvae are often found in the coelom or peritoneum of dogs, Felis catus, mice, snakes, and other vertebrates; the adult form is found in the intestines of carnivorous animals, including man, dogs, Felis catus, racoons, and meat-eating birds.
• Dipylidiidae
• Dipylidium, found in Felis catus and other small carnivores
• Dipylidium caninum (a.k.a. Taenia elliptica)
Transmission : reservoir : Canis familiaris, Vulpes vulpes, and Felis catus, the larval stage living in fleas (Ctenocephalides canis) and lice (Trichodectes canis) of dogs, as well as in Pulex irritans, which thus act as vectors
=> dipylidiasis : abdominal pain, diarrhea and itch
• Hymenolepididae
• Hymenolepis
• Hymenolepis diminuta (a tapeworm of Rattus spp. and Mus spp., occasionally found in man)
• Hymenolepis lanceolata (a species that infects Anser spp. and Anas spp. and has been reported in a human being)
• Hymenolepis nana (a.k.a. Taenia nana, Vampirolepis nana) : the dwarf tapeworm, a species about 7 to 80 mm long that is parasitic in Rattus spp., Mus spp., and man, especially children. Hymenolepis fraterna is the rodent form of H. nana; often called H. nana var. fraterna.
Transmission : fecal-oral route (expecially common in institutions) ingestion of embryo (exacanthus => cysticercoid).
=> hymenolepiasis :
• asymptomatic
• in massive infection symptoms may include dizziness, anorexia, abdominal pain, flatulence, diarrhea, insomnia, irritability (epilepsy and chorea in babies)
Treatment : praziquantel 25 mg/kg in 1 p.o. dose. Jarisch-Herxheimer reaction (JHR) can occur.
• Taeniidae [L. “a flat band,” “bandage,” “tape”]  : a family of medium-sized or large tapeworms which are parasitic in mammals, including man; medically important genera are :
• Echinococcus
• hydatid : larval stage in which there are multiple compartments containing protoscolices as well as inverted scolices, may be metastatic.
• hydatid sand / calcareous granules : the mineral deposits formed within a hydatid cyst viewable under Rx.
• brood capsules : capsular projections from the internal membrane of hydatid cysts, from which the scoleces arise
=> echinococcus disease / echinococciasis / echinococcosis / hydatidosis / hydatid disease
• Echinococcus granulosus (a.k.a. Taenia echinococcus)
Epidemiology : approximately 2000 people are surgically treated for echinococcosis every year in Kazakhstan. In rural areas of the Zhambylskiy region, for example, 50% of dogs are infected by Echinococcus. The highest rates of echinococcosis are reported from the southern region. The rates of surgical disease have been increasing since 1990^ref. Approximately 100 to 200 cases per year were reported during 1974 to 1990 (0.9 to 1.4 per 100 000). 39 cases were reported among children in 1993, and 112 in 1997. In 2000, 29% of cases reported were in children below age 14 years, with rates of 5.9 per 100 000. Prevalence surveys: 5.8% of village dogs and 23.2% of shepherd dogs are infected. Seroprevalence surveys: 3.1% of the population in southern Kazakhstan are infected, and 6.1% of shepherds. Infected rodents (Ondrata zibethica) are found in the Illi and Karatal river valleys and surrounding lake regions. Infected Rhombomys opimus are present in oasis settlements, desert hills and areas of sand and clay deserts. Infected soil is identified in the rural south
Proteomics : EgTeg is a 105 amino acid protein that inhibits polymorphonuclear cell (PMN) chemotaxis and T_h1 polarization^ref
Transmission : ingestion of food contaminated by stools of infected Canis familiaris, Canis lupus, Ovis aries or Camelidae, and occasionally Felis catus.
=> cystic hydatidosis / cystic hydatid disease / unilocular hydatid disease : Echinococcus embryos are trapped in various organs (=> hepatic hydatidosis => heart => pulmonary hydatidosis
• Bird's sign : a definite zone of dullness with absence of the respiratory sounds in hydatid disease of the lung.
=> brain, kidney and rarely (2÷3 %) bones (50% in thoracic or lumbar vertebra) or muscles) and develop into thin walled, fluid-filled unilocular hydatid cyst(s) with Ø < 5 cm, which grow and eventually cause symptoms of space-occupying lesions in the tissues or organs affected. Bacterial overinfection may lead to formation of abscesses, while rupture may cause anaphylactic shock and secondary hydatidosis (also hydatid vomiting if fistula drains into bronchus).
• sterile cyst / acephalocyst : a true hydatid cyst that fails to produce brood capsules
• daughter or secondary cyst : a small parasitic cyst developed from the wall of a larger one
• osseous hydatid cysts : hydatid cysts occurring in bone, which may become weakened and eroded by the exuberant growth.
Laboratory examinations :
• abdomen scans (echography, X-ray, NMR, CT)
• detection of specific antibodies (Ghedini-Weinberg complement fixation, Casoni's intradermoreaction, RAST, arc 5 search)
• IgG₄ specific to EgTeg give acceptable sensitivity (65%) and high specificity (89%)^ref
• Echinococcus multilocularis (a.k.a. Echinococcus alveolaris)
Transmission : animal skinning or ingestion of vegetables contaminated by faeces of Vulpes spp. or wild Rodentia
=> alveolar hydatidosis / alveolar hydatid disease (AHD) : spread stops in liver (they may metastasize later). Invasion and destruction of tissues as the cysts undergo endogenous budding to form an aggregate of small cysts that honeycomb the affected organ. Multilocular hydatid cyst is asymptomatic, especially in the lengthy early stages (> 30 years !), when it can be detected by echography : only dyspepsia and obstructive jaundice. Spontaneous evolution is lethal and surgical therapy if often unpracticeable. In humans, brood capsules and scolices are rarely present.
• multilocular cyst : a hydatid cyst with many small irregular cavities that may contain scoleces but generally little fluid; it tends to enlarge by budding since it has a poorly developed hyaline cuticle
Symptoms & signs :
• Lennhoff's sign : a furrow appearing on deep inspiration below the lowest rib and above an echinococcus cyst of the liver.
• Rovighi's sign : a fremitus felt on percussion and palpation of a superficial hepatic hydatid cyst.
• Dew's sign : in diaphragmatic hydatid abscess beneath the right cupola, the area of resonance moves caudally with the patient on hands and knees
• echo sign : a percussion sound resembling an echo which is heard over a hydatid cyst
Therapy : surgical cyst(s) ablation after percutaneous evacuation (echinococcotomy) and killing (NaCl 30% or ethanol 95%) is recommended as cyst(s) rupture may cause anaphylactic shock. Pre- and post-operative drug treatment includes albendazole (800 mg/die) or mebendazole (1,800 mg/die) or praziquantel per 5 weeks - all with poor cure rates.
• Echinococcus oligarthrus
• Echinococcus vogelii : a species found in Central America and northern South America; its adult form parasitizes canids and its larvae have as intermediate hosts the paca, agouti, and other rodents
• Taenia
• Taenia taeniaeformis (a.k.a. Taenia crassicollis)

Transmission : a species commonly found in Felis catus, and more rarely in Canis familiaris (2.9%), Vulpes spp., and other animals, having rats, mice, and other rodents (Oryctolagus cuniculus) as intermediate host
• Taenia pisiformis (a.k.a. Coenurus cerebralis)

Transmission :  commonly found in Canis familiaris, Bos taurus, Ovis aries and also parasitic in Felis catus, Vulpes spp., Canis lupus, and other animals; the cysticercus (larval stage) is found in the liver and peritoneal cavity of Oryctolagus cuniculus
=> circling, aggression, blindness and ataxia
• metacestode (larval) stage = cysticercus (single scolex enclosed in a bladderlike cyst)

Transmission : ingestion of eggs
• ingestion of food, vegetables, or water contaminated by the eggs present in the infectious feces of a Taenia carrier, eg from latrines used as fertilizer or aerial spraying of fruit and vegetable crops using fecally contaminated water. This requires that these items be contaminated by human feces, as infected pigs do not shed eggs. This fact can also explain how people who never ever eat pork, such as orthodox Jews, are still at risk of acquiring this disease^ref
• anus-hand-mouth transfer of the eggs by contaminated hands of persons with poor personal hygiene (endogenous autoinfection)
• reverse peristalsis in which eggs produced by T.solium are thrown back to the duodenum, where they hatch and cause tissue infection (autoinfection)
When in bowel eggs develop into cysticerci, which penetrate the intestinal wall => cysticercosis after 15 days to some years: in various animals it occurs as cysts found in striated muscles and causes no adverse symptoms (called also beef measles, pork measles, and sheep measles). Cysticercosis in humans can be of the following types:
• muscular and subcutaneous cysticercosis: any muscle mass may be involved in the condition. Most patients are asymptomatic. Symptomatic cases present as acute myositis. Cysticerci in muscles often are associated with neurocysticercosis. Subcutaneous nodules (a very common manifestation in Vietnam and is also seen in other Asian countries, African countries such as Zambia) are mostly asymptomatic.
• ocular cysticercosis : cysticerci are present in an eye in about 20% of cases. Most cysts are found in the vitreous, subretinal space, and conjunctiva. The condition may present as iritis or iridocyclitis, uveitis, palpebral conjunctivitis, strabismus, scotomas, ophthalgia, blindness. The cysts in subconjunctival or subretinal sites may present as slowly growing nodules, presenting the possibility of confusion with tumors. Occasionally, subretinal eye cysts may lead to blindness due to detachment of the retina. Fundoscopic examination may show free-floating cysticerci in the anterior chamber and vitreous chamber. This helps in the visual identification of the movements and morphology of larval forms. Larvae may be found attached to subretinal tissues.
• neurocysticercosis (NCC) / cerebral cysticercosis : this  is the most serious form of cysticercosis. The condition is seen in 60-90% of cases of cysticercosis. NCC is a common cause of neurological disease in India.  It is one of the common causes of epilepsy in children. It is second only to tuberculosis as the most common important space-occupying lesion of the brain. The clinical manifestations in the CNS are highly variable and depend on the:
• number, location and viability of cysts
• stage of development of the cyst -- whether young and mature or intact and degenerated
• host response against the cyst
NCC is of 2 types:
• parenchymal disease is caused by infection of the brain parenchyma with cysticerci. This is the most common form of NCC
• extraparenchymal disease is caused by location of cysts in the cerebrospinal fluid (CSF) of the ventricles, cisterns, and subarachnoid space or in the spinal cord.
Commonly, 1 to 5 cysts are found, but in some patients as many as 200 cysts have been reported. Convulsions and/or seizures, intracranial hypertension, and psychiatric disturbances are the 3 important manifestations of the NCC. These may occur separately or in combination. Onset can be insidious or abrupt. Convulsions and/or seizures are caused by the presence of cysticerci in the brain parenchyma. Seizures are the most common clinical manifestations and occur in 70-90% of cases. Seizures in children are focal with acute onset. In endemic areas, cysticercosis is the most common cause of epilepsy. Meningeal cysts may manifest as meningitis. The cysts of intramedullary spinal cord cysts can produce motor or sensory disorders.  Intracranial hypertension is caused by obstruction of CSF by the cysts, which are found in the ventricles of the brain. Headache, nausea and vomiting, vertigo, and altered mental status are the presenting symptoms. Intracranial herniations, stroke, and status epilepticus are the most important complications of neurocysticercosis
Prognosis : nearly 10% of patients with cerebral lesions die within 5 years to 10 years of developing the illness^{ref1, ref2}.
• heart
• spinal cord (paralysis)
• liver
• lung
• peritoneum
Aetiology :
• Taenia cellulosae (metacestode : Cysticercus cellulosae)
• Taenia hydatigena (a.k.a. Taenia marginata) : a species parasitic in Canis familiaris and wild Carnivora; the larval stage (cysticercus) is found in the liver and abdominal cavity of various ruminants and Rodentia and occasionally in other animals, including humans
• Taenia saginata (a.k.a. Taenia africana, Taenia cucurbitina, Taenia mediocanellata, Taenia philippina, Taeniarrhynchus saginatus, beef or unarmed tapeworm; metacestode : Cysticercus bovis)
• Taenia confusa (a.k.a. Taenia bremneri) a species found in the Mississippi Valley and in East Africa, believed by some to be a variant of T. saginata
=> taeniarhynchosis in humans who eat incompletely cooked beef may become infected and it can grow to a tapeworm 4 to 8 m long in the intestine
• Taenia solium (a.k.a. pork tapeworm; metacestode : Cysticercus racemosus) : 1 to 2 meters long found in the adult form in the human intestine; the cysticerci (larval stage) occur most often in the muscle and various tissues of the Sus scrofa, but are also found in man, monkeys, Camelidae, Ovis aries, and Canis familiaris
• metacestode (larval) stage = coenurus (semitransparent fluid-filled organisms that contain multiple scoleces attached to the inner surface of the cavity wall)
• Taenia brauni (?)
• Taenia glomerulatus (?)
• Taenia multiceps (a.k.a. Multiceps multiceps ; larval stage : Cenurus cerebralis) is found in the brains of Ovis aries (causing gid / staggers), as well as in brains of Canis familiaris, Capra hircus, and other ruminants)
• Taenia serialis (a.k.a. Multiceps serialis) : a species whose adult stage is parasitic in Canis familiaris; its larval stage develops in the connective tissues of Oryctolagus cuniculus, squirrels, other Rodentia, and occasionally humans.
Transmission : ingestion of eggs, which when in bowel develop into cenuri => coenurosis / coenuriasis : CNS cysts that obstruct the outflow of CSF and cause intracranial hypertension that can be fatal
Transmission : ingestion of cysticerci in pork muscles, which develop into adult tapeworms when in human bowel => intestinal taeniasis (presence immunity => "lonely worm") :
• asymptomatic
• dyspepsia, abdominal pain, diarrhea, irritability
Adult worms excrete tens of thousands of eggs in feces, which in turn may infect pigs and man
Laboratory examinations :
• demonstration of gravid proglottids of T.solium passed in the feces. Eggs of Taenia solium and Taenia saginata are morphologically indistinguishable.
• anti-cysticercus antibodies in serum or CSF
• ELISA is a useful method for demonstration of antibodies in the serum as well as in the CSF, but detection of antibodies in CSF provides better reliability. The test has a low sensitivity (75%) and specificity (85%). It shows false positive reactions with sera from other helminthic infections. ELISA is useful to diagnose NCC patients with few CNS lesions and relatively mild disease.
• enzyme-linked immunoelectrotransfer blot (EITB) assay using a purified fraction of glycoprotein (Gp) is highly specific (100%) for detection of antibodies both in the serum and CSF. The presence of 1-7 specific glycoprotein (Gp) bands is considered diagnostic of T.solium infection. The test is more than 90% sensitive in NCC patients with more than 2 cysticerci in the brain; sensitivity declines to 50-70 % with a single cysticercus. The assay, therefore, is of limited value in children, because most of them in India have a single lesion. A serum immunoblot assay is more sensitive than the test using CSF.
Antibody detection in cysticercosis has 2 important disadvantages:
• it may indicate only exposure to infection. It does not indicate whether the patient has established and viable recent infection
• antibody titres continue to persist in the serum even after the parasite has been eliminated through the immune mechanism and/or following drug therapy
Detection of antigen in  serum or CSF indicates recent or viable infection.  Antigen can be detected in the serum or CSF by ELISA using specific monoclonal antibodies.  These antigen detection tests are highly sensitive and  specific.
Imaging methods supplement the diagnosis of NCC :
• plain x-ray of the soft tissues in arms, thigh, chest, and neck may show dead calcified oval or elongated cysts. A central calcified scolex surrounded by a calcified cyst wall is pathognomonic. X-ray of the skull may demonstrate cerebral calcification and reveal intracranial lesions produced by neurocysticercosis.
• computed tomography (CT) and magnetic resonance imaging (MRI) are the main imaging  methods used now for the diagnosis of neurocysticercosis.  They help to
• identify the cysticerci
• demonstrate the number, site, and stage of the cysticerci  present in the brain
CT is the best method for detecting dead, calcified, and multiple cysts.  The dead worms are visible as round hypodensities, often with the protoscolex mouth of the parasite appearing as an eccentric dot of calcium. CT is superior to MRI in the detection of intracerebral calcification. A central calcified scolex surrounded by a calcified cyst is pathognomonic of neurocysticercosis. A CT scan with contrast shows a ring-enhancing image (signifying edema) surrounding an involuting living cysticercus. MRI is superior to a CT for demonstration of :
• non-calcified cysts
• cysts in the brain parenchyma, particularly near base of the brain
• cysts in extraparenchymal sites (intraventricular and cisternal cysts)
MRI shows a mural nodule within the cyst, which is pathognomonic for NCC.
Therapy :
• taeniafuge / teniafuge / tenifuge (an agent that expels tapeworms) : praziquantel and niclosamide for the treatment of intestinal taeniasis caused by T.solium. Asymptomatic neurocysticercosis requires no treatment. Treatment for symptomatic NCC is chemotherapy by albendazole or praziquantel -- the latter is the drug of choice.  The drug is given in an oral dose of 50 mg/kg body weight in 3 divided doses for 15 days. Praziquantel is usually given along with corticosteroids to reduce the inflammatory reactions caused by the dead cysticerci.
• surgery is indicated for cysticercosis of ocular, ventricular, and spinal cord, because treatment with anthelminthic drugs can provoke irreversible drug-induced inflammation.
• Pseudophyllidea : an order of cestodes in which the scolex typically has two opposing sucking organs.
• coracidium : the individual free-swimming or free-crawling, spherical, ciliated embryo of tapeworms of the order Pseudophyllidea
It includes the family ..
• Diphyllobothriidae : a family of cestodes that are parasitic in man and other fish-eating vertebrates. The genera of medical importance are :
• Diphyllobothrium (formerly called Bothriocephalus and Dibothriocephalus)
• Diphyllobothrium alascense

Epidemiology : occasionally found in Eskimos
• Diphyllobothrium cordatum : the heart-headed tapeworm; a small species

Transmission : found in Canis familiaris and in seals and very rarely in humans
Epidemiology : in Greenland
• Diphyllobothrium dalliae

Epidemiology : from Alaska and Siberia
Transmission : in Alaskan blackfish
• Diphyllobothrium dendriticum (Nitzsch, 1824)

Epidemiology : occurs throughout the circumpolar area at high latitudes beyond the range of D. latum
Transmission : larvae of D. dendriticum occur predominantly in salmonid fishes (e.g. arctic char, salmon, trout, whitefish), and this parasite has never been found in pike and perch, the usual intermediate hosts of D. latum.
• Diphyllobothrium ditremum(Creplin, 1827).
• Diphyllobothrium erinacei (formerly called Diphyllobothrium mansoni)

Transmission :a species found in the adult form in Canis familiaris and other carnivores
• Diphyllobothrium klebanovskii

Epidemiology : from Siberia
Transmission : predominantly occur in Pacific salmon, infects humans
• Diphyllobothrium latum (a.k.a. broad or fish tapeworm, Dibothriocephalus latus and formerly Diphyllobothrium taenioides, or bothriocephalus) : its head has 2 grooves or suckers (bothria). The egg and proglottids (segments) are easy to be distinguished from segments from other human tapeworms, including Taenia saginata (beef tapeworm) or Taenia solium. Diphyllobothrium latum was 1st described by Linnaeus in 1758, long before sushi became popular outside Japan

Epidemiology : diphyllobothriasis is certainly a re-emerging parasitic zoonose. A recent European survey identified dozens of  cases in Finland, Sweden and in the French- or Italian-speaking areas of the subalpine lakes^ref. > 30 cases of diphyllobothriasis have been identified on the Swiss shores of Lake Maggiore since 1990, and 70 cases on the Swiss and French shores of Lake of Geneva between 1993 and 2002. Plerocercoid larvae were found in 7% of 200 perch fillets from the Lake of Geneva.
Transmission :
• first intermediate host : a freshwater crustacean. It is therefore not found in strictly saltwater fish.
• second intermediate host : only freshwater fish or species that spend part of their life in fresh water (the worm lives in the musculature of the fish (rarely found in salmonids : in the case of salmon, it is found in the nerves); also robalo (Centropomus undecimalis, a large serranoid food fish found on both coasts of America, also variously known as sea pike, garfish, cobia, and Spanish bass) => ingestion of raw (sushi and sashimi), smoked, or incompletely cooked fish =>
• found in the intestines of humans, Felis catus, Canis familiaris, Sus scrofa, Vulpes vulpes, mink, bears, and other fish-eating mammals, where it can live up to 10 years and achieve a length of 9 meters, but eggs shed from these species are usually less infective than eggs shed from humans. Humans start shedding eggs about 6 weeks after infection and, to maintain the infectious cycle, eggs from human waste must pollute fresh water, where the intermediate host -- the copepod (Diaptomus vulgaris) -- is infected and later ingested by fish. Alternatively, the fish can be infected by eating another infected fish.Some asymptomatic patients, including children, become aware of the infection when they observe pieces of the parasite in their feces.
Prevention : fish that wil be consumed raw should be freezed for a minimum of 24 hours at -18°C
Therapy : a single dose of praziquantel
Diphyllobothrium nihonkaiense Yamane et al., 1986

Epidemiology : Japan^ref
Transmission : Oncorhynchus masou ishikawae^ref
Laboratory examinations : RFLPs in the digested profiles with SmaI, HinfI and HhaI could be used as species-specific markers even if only fragments of strobilae with morphological similarity were available^ref.
Therapy : a single oral dose of 7, 23 or 25 mg/kg of praziquantel (also low-dose with at 5-10 mg/kg^ref). All patients expelled the tapeworm with scolex, and no side effect was noted^{ref1, ref2}; oral administration of Gastrografin in combination with a intramuscular injection of Vagostigmin^ref.
Diphyllobothrium pacificum (Nybelin, 1931) Margolis, 1956

Epidemiology : in South America, cases have been confirmed in Chile^{ref1, ref2, ref3} (Torres P, Gesche W, Montefusco A, Miranda JC, Dietz P, Huijse R. Diphyllobothriasis humana y en peces del lago Riñihue, Chile: efecto de la actividad educativa, distribución estacional y relación con sexo, talla y dieta de los peces. Archivos de Medicina Veterinaria. 1998;30:31–45), Peru (Flores JM, Vidaurre MT, Rivera ML, Rosales MC. Diphyllobothrium pacificum en niños del Peru. Diagnóstico. 2002;41:161–4; even from precolumbian coprolites^{ref1, ref2} and mummies dated between 4,000 and 5,000 years ago, smaller than usual eggs due to release of immature eggs into the intestinal tract as the tapeworms decompose after the death of the host^ref), southern Brazil^ref, Uruguay, and Argentina^ref. New cases were clearly associated with a cyclic manifestation of El Nino in the Chilean Pacific coast during 1975-2000 due to the migrations of sylvatic mammals, fishes and birds as well as by environmental contamination^ref. Also identified in a sample taken in the abdominal cavity of a child skeleton found in Zeto Point (ADK-011), an archaeological site on Adak Island in the Central Aleutian Islands (Alaska)^ref
Transmission : the intermediate host is only saltwater fish. Sea lions and fur seals host the adult worm. South American sea lions and fur seals live along the cost of Peru, Chile, Argentina and Uruguay. It will therefore be unlikely to find infected fish out of the living range of the sea lions/fur seals. D. pacificum does infect in Canis familiaris^{ref1, ref2} and humans, and is not uncommon among Peruvians and Chilean eating  raw fish (Sciaena deliciosa) with lemon in a traditional plate called "cebiche"^{ref1, ref2}
Therapy : praziquantel^ref
Diphyllobothrium stemmacephalum Cobbold, 1858^ref
Diphyllobothrium ursi Yamaguti, 1941

Epidemiology : in North America. Most cases occur in Michigan, Minnesota, California, Florida, Northern Canada, British Columbia^ref and Alaska (natives)^ref
Transmission : predominantly occur in Pacific salmon; isolated from free-ranging black bears, Ursus americanus Pallas, 1780, from northeastern Minnesota or northern Michigan^ref
Transmission : ingestion of contaminated raw fish or copepods
Symptoms & signs : => bothriocephalosis / bothriocephaliasis / diphyllobothriasis :
• asymptomatic (80%)
• symptomatic (20%) : pain and abdominal discomfort, flatulence, and diarrhea. There can also be associated vomiting, weight loss, and pernicious anemia, since the parasite absorbs vitamin B₁₂ from the host (0.5%)
Species other than D. latum probably constitute transitory intestinal infections in humans, usually lasting for only a few months. Although many carriers are asymptomatic, overt clinical manifestations of diphyllobothriasis can include diarrhea, epigastric pain, nausea and vomiting. There are no reports of anaemia associated with any of the northern species except D. latum.
Laboratory examinations : if the precise identification of the genus Diphyllobothrium is quite easy for a keen parasitologist by examining the proglottids, the species identification is particularly difficult. Routine diagnosis of diphyllobothriasis by coprology does not allow designation of the Diphyllobothrium species involved as their eggs cannot be differentiated and identification of the proglottids from adult worms requires a taxonomic specialist. On the other hand, relevant information on the Diphyllobothrium species most likely to infect the inhabitants of a particular region can be derived from a knowledge of the fish consumed. Therefore a molecular analysis on the Diphyllobothrium spp. genus by genotyping different genes (COI, ITS1, rDNA 18S.) has been developed. By this method, proglottids or plerocercoids preserved in alcohol can be identified.
Prevention : effective control for diphyllobothriasis originating from D. latum has been achieved in many areas by a combination of selective drug therapy and improved sewage treatment.
• Spirometra
• Spirometra erinaceieuropaei : a species parasitic in man, Canis familiaris, and Felis catus.
• Spirometra mansonoides : a species parasitic in Canis familiaris and Felis catus, especially bobcats, which may cause diarrhea and anemia; infection with the larvae may cause sparganosis in man.
Transmission : eating inadequately cooked fish; reservoir : fish-eating Felis catus, Canis familiaris, and birds
=> sparganosis : infection with migrating spargana (sparganum is the larval stage (plerocercoid) of certain cestodes, especially of the genera Diphyllobothrium and Spirometra), which invade the subcutaneous tissues of humans and other animals, causing inflammation and fibrosis that resembles cellulitis
• cestodic tuberculosis : a disease simulating tuberculosis, but due to excessive infestation with cestode parasites.
• Trematoda : most are parasitic in humans or other animals, infection generally resulting from the ingestion of uncooked or undercooked fish, crustaceans, or vegetation. All flukes require a mollusk as their first intermediate host, in which a complex developmental cycle takes place. The larval stage, which escapes from the mollusk, may then enter a second intermediate host (fish, crustacean, or another mollusk), encyst on vegetation, or penetrate directly into the skin of the definitive host.
• redia [named after F. Redi, Italian naturalist, 1626–1698] : a larval stage of certain trematode parasites, which develops in the body of a snail host and gives rise to daughter rediae, or to the cercariae.
• Digenea (flukes)

Cercariae escape from the first intermediate host and encyst in or on a second intermediate host forming metacercariae. When the second intermediate host is eaten the metacercariae excyst in the definitive host's intestinal tract, thus establishing an infection.
=> trematodiasis / fluke disease / distomiasis / distomatosis
• intestinal trematodiases
• Echinostomida
• Echinostomata
• Echinostomatidae
• Echinochasmus : a genus of parasitic intestinal flukes
• Echinochasmus perfoliatus

Epidemiology : Japan.
• Echinostoma : a genus of parasitic flukes
• Echinostoma revolutum is found in the intestines of ducks and geese and has been reported in humans

Epidemiology : Taiwan and Indonesia
• Echinostoma ilocanum (?) has been found in human feces

Epidemiology : Indonesia and the Philippines
=> intestinal distomiasis
• Echinostoma lindoensis occurs in Indonesia
• Echinostoma perfoliatum

Epidemiology : Japan
=> echinostomiasis
• Fascioloidea
• Fasciolidae
• Fasciola
Fasciola gigantica : a giant liver fluke that infects Bos taurus, Ovis aries, wild animals, and occasionally humans

Epidemiology : Africa, Asia, and Hawaii.
Fasciola hepatica (a.k.a. Distoma hepatica, Distoma hepaticum, liver-dwelling fluke)

Epidemiology : Europe, North Africa, Cuba, South America. A single U.S. case (1984) was published in the world's literature during 1969 to 1989. The local reservoirs are Lymnaea collumella, Fossaria bulimoides and Fo. cubensis.  Fo. cllula carries Fasciola gigantica in Hawaii.
Transmission : the common liver fluke of sheep, oxen, goats, horses, and other herbivorous animals. It is occasionally found in the human liver, where it may cause dangerous symptoms by obstructing the biliary passages and by invasion of the liver parenchyma. Several snails of the genus Lymnaea act as invertebrate hosts => ingestion of contaminated water or water-dwelling vegetation, e.g., watercress (parasite of herbivores)
=> fascioliasis / hepatobiliary distomiasis 2-3 weeks incubation
• acute fascioliasis is characterized by fever, abdominal pain (especially hepatic), nausea and vomiting, diarrhea, and hepatomegaly. Cough may also occur. Transaminitis and increased, ESR; anemia is common
• halzoun : a pharyngeal form of fascioliasis occurring in the Middle East, caused by eating raw animal livers infected with Fasciola; young adult worms attach to the pharyngeal mucosa and produce pain, bleeding, and facial and neck edema
• chronic fascioliasis results in a variety liver and gallbladder abnormalities
Therapy : bithionol 30-50 mg/kg orally qod for 10-15 doses is the treatment of choice as this is written. Triclabendazole in a single dose of 10 mg/kg may become the drug of choice when available.
• Fascioloides
• Fascioloides magna (a.k.a. Fasciola magna) is a large fluke found in the liver and lungs of herbivorous animals in North America.
• Fasciolopsis
• Fasciolopsis buski
It is the largest of the intestinal flukes
Epidemiology : 10 million people prevalence in Orient
Transmission : reservoir : found in the small intestine of Sus scrofa; 25,000 eggs/day. The intermediate hosts are the snails Planorbis coenosus and various species of Segmentina.
=> fasciolopsiasis / intestinal distomiasis in small intestine : nausea, diarrhea, and a malabsorption syndrome if present in large numbers
• Opisthorchiida
• Opisthorchiata
• Opisthorchioidea
• Heterophyidae

Epidemiology : the following species of heterophyid trematodes are known to infest humans in the Philippines:
• Carneophallus (Heterophyes brevicaeca, Spelotrema brevicaeca) - acquired from raw shrimp.
• Centrocestus formsanus, a parasite of rats, cats, dogs, chickens and ducks - acquired from freshwater fish and frogs.
• Diorchitrema pseudocirratum, Haplorchis pumilio, a parasite of cats and dogs - acquired from ingestion of freshwater fish.
• Haplorchis taichui - acquired from freshwater fish. 36.0% of persons in San Isidro, Compostella Valley are infested (2000).
• Haplorchis vanissimus, Haplorchis yokogawi, a parasite of cats and dogs - acquired from ingestion of shrimp and mullet.
• Hetrerophyopsis continua, a parasite of cats - acquired from fish (Mugil cephalus, Mugil affinis, Larus argentatus, Cyprinus carpio).
• Procerovum calderoni, a parasite of cats and dogs - acquired from fish.
• Stellantchasmus falcatus, a parasite of cats, dogs and birds - acquired from fish (Mugil cephalus)
• Heterophyes : a genus of minute trematodes of the family Heterophyidae, found in the middle third of the small intestine of humans, Canis familiaris, Felis catus, and other fish-eating mammals.
• Heterophyes brevicaeca have been reported in humans in Japan and the Philippines
• Heterophyes heterophyes is found in Egypt, Asia, and Turkey
• Heterophyes katsuradai
• Heterophyes nocens (a.k.a. Heterophyes heterophyes)
Epidemiology : a stool survey conducted in Monkayo, Compostela Valley, the Philippines found that 36% of patients with history of bowel disturbance (abdominal discomfort/pain and/or diarrhea) in the past 4 weeks were found to have heterophyidiasis. All age groups were infected, with the youngest patient being 1 year 7 months of age, while the oldest patient was 73 years of age. Prevalence was highest in the age group 15-30 years at 55.3%^ref
Transmission : fish that live in fresh or brackish water are the 2nd intermediary host. There is no risk of infection from saltwater fish, and infection can be prevented by cooking fish adequately
=> heterophyiasis / heterophydiasis / intestinal distomiasis : it is generally asymptomatic. The main symptoms are intestinal, but occasionally the eggs may migrate to the heart, resulting in potentially fatal myocardial and valvular damage, and to other organs (e.g., brain)
• Metagonimus
• Metagonimus yokogawai (a.k.a. Metagonimus ovatus) is found in the small intestines of humans and other mammals in East Asia, Indonesia, Israel, and the Balkans.

=> intestinal distomiasis / metagonimiasis : chronic enterocolitis
Therapy : 10 mg/kg of azinox^ref
• Opisthorchiidae : characterized by having the testes near the posterior end of the body.
• Clonorchis
• Clonorchis sinensis (a.k.a. Distoma sinensis, Opistorchis sinensis)
Epidemiology : China, Japan, Korea, Taiwan, and Indochina. In China, clonorchiasis infections have more than tripled over the past decade; 15 million people were infected in 2004^ref
Transmission : found in the bile ducts of humans, Felis catus, Canis familiaris, and other species that consume contaminated raw fresh water fish, shellfish containing larvae or marine vegetables. Larval development requires 2 intermediate hosts, the first a snail of the genus Parafossarulus manchouricus (family : Bulinidae; a species found in eastern Asia and nearby islands. It is the foremost intermediate host of the liver fluke Opisthorchis sinensis in Japan and the second most important in China, as well as a carrier of the flukes O. felineus and Echinochasmus perfoliatus) or Bithynia, the second a fresh water fish of the carp family.
=> clonorchiasis / clonorchiosis 2-3 weeks incubation :
• intestinal distomiasis
• hepatobiliary distomiasis : infestation of biliary passages, which may lead to cholangiohepatitis, proliferation of the biliary epithelium, progressive portal fibrosis, and sometimes cholangiocarcinoma; extension into the liver parenchyma may lead to fatty changes and cirrhosis
• Metorchis
• Metorchis albidus parasitize Felis catus, Canis familiaris, and other mammals.
• Metorchis conjunctus (Cobbold, 1860)
Epidemiology : found in carnivores from South Carolina to the Northwest Territories.
Transmission : ingestion of contaminated water or water-dwelling vegetation, e.g., watercress, raw fish (sashimi) prepared from the white sucker, Catostomus commersoni, caught in a river north of Montreal, Canada; reservoir : Felis catus, red foxes, fisher (Martes pennanti), wolves (Canis lupus: cholangiohepatitis with periductular fibrosis in the liver and chronic inflammation and fibrosis of the pancreas)
=> hepatobiliary distomiasis / metorchiasis after 2-3 weeks : upper abdominal pain, low grade fever, high blood eosinophil concentrations, and raised liver enzymes for 3 days to 4 weeks without treatment
Laboratory examinations : opisthorchild-like eggs were found in stools after 10 days
Treatment : praziquantel
• Opisthorchis : a genus of characterized by having the testes near the posterior end of the body.
• Opisthorchis felineus (a.k.a. Siberian liver fluke)

Epidemiology : Obskoye Sea (Novosibirsk oblast, Russia) : 13% of the reservoir's bream, along with 70-80% of dace, 15% of roach, and 75% of ide. The main source of opisthorchiasis is the lower stream of the Ob river, in the Hanti-Mantiyskiy region. Novosibirsk itself is now becoming a source of opisthorchiasis, however, because of its sewage disposal system -- the cities of Kamenka, Elzovka, and Tula are all dumping their contaminated sewage into the Ob river. The Vengerskiy region has the highest human opisthorchiasis rate -- 1030 people have been diagnosed with this parasite. This is not a precise prevalence rate, however, because it was obtained from among people in high-risk groups.
Transmission : ingestion of raw liver of infected fish, such as Leuciscus rutilis, Idus melanotus, and related species; reservoir : Felis catus, Canis familiaris, Sus scrofa
• Opisthorchis tenuicollis : a species found in the bile ducts and sometimes the intestines of Felis catus, Canis familiaris, Sus scrofa, and sometimes other mammals including humans.
• Opisthorchis viverrini : a species that causes opisthorchiasis in Prionailurus viverrinus and sometimes humans

Epidemiology : Thailand.
Transmission : ingestion of contaminated raw fish (carps), shellfish or marine vegetables. The final hosts include human, Canis familiaris, and Felis catus, all of which get infected from eating raw or undercooked fish. Eggs are excreted in feces and hatch into miracidia after being ingested by snails, transform into free-living cercaria, which penetrate and encyst (metacercaria) in susceptible fish species. When ingested by humans, cats, or dogs the metacercaria excyst and migrate to the intrahepatic bile duct system, where they can live for years
=> opistorchiasis / hepatobiliary distomiasis / opisthorchosis : infection of the biliary tract. In heavy infections there is local injury to the distal bile capillaries and surrounding liver tissue; after 2-3 weeks : normal temperature, general malaise, skin rash, and gastrointestinal disturbances. Severe anemia and liver damage incapacitate the infected person for 1-2 months. Once they reach the human liver, larvae can mature into the parasite and live for 25 years. The long-term complications are biliary duct constrictions, cirrhosis of the liver with areas of necrosis and fatty degeneration, and cholangiocarcinoma
Treatment : praziquantel in a single dose is usually effective and has been used in mass treatment campaigns
Prevention : proper cooking of fish (worms die if the fish is boiled for 20' or cooked in the oven for 40'. Hot smoking kills flukes but not cold smoking)
• Parametorchis
• Pseudamphistomum (a.k.a. Pseudoamphistomum)
• Pseudamphistomum truncatum is found in the bile ducts of Felis catus, dogs, seals, deer, and occasionally humans in Europe and India and causes a condition resembling opisthorchiasis.
• Paramphistomatida : pear-shaped trematodes (paramphistome / amphistome / conical fluke) that have the sucker near the posterior end and infest the intestines of ruminants and occasionally humans or other mammals
• [Paramphistomatoidea : a superfamily of trematodes that includes the family Paramphistomatidae]
paramphistome / amphistome / conical fluke : any member of the family Paramphistomatidae, pear-shaped trematodes that have the sucker near the posterior end and infest the intestines of ruminants and occasionally humans or other mammals
=> paramphistomiasis / amphistomiasis : infestation by intestinal flukes of the family Paramphistomatidae. Most genera are usually found in the stomachs or small intestines of ruminants
• Gastrodiscoides (a.k.a. Gastrodiscus) ; many are parasitic in the intestinal tract
• Gastrodiscoides hominis

Epidemiology : India, Indochina, and Malaysia
Transmission : found in the cecum and colon of Sus scrofa
=> gastrodisciasis in humans and swine in southeastern Asia
• Watsonius [Malcolm Watson, British physician, 1873–1955] : genus of pear-shaped trematodes of the family Paramphistomatidae.
• Watsonius watsoni (formerly called Amphistoma watsoni)

Epidemiology : Africa
Transmission : monkeys
sometimes found in the duodenum of humans and other animals. Adult worms may be present without any clinical signs, but immature worms cause more severe manifestations such as enteritis, severe diarrhea, anorexia, and hemorrhaging. In flocks of Bos taurus or Ovis aries with heavy infestations, the mortality may be over 90%
• Paramphistomum
• Paramphistomum cervi is found in the rumen and reticulum of ruminants,
• Plagiorchiida
• Plagiorchiata
• Plagiorchioidea
• Dicrocoeliidae : a family of trematodes that infect the liver, pancreas, and bile ducts of various animals and occasionally humans.
• Dicrocoelium
• Dicrocoelium dendriticum (a.k.a. Dicrocoelium lanceolatum, lancet fluke)
Epidemiology : North and South America, northern Africa (Egypt), and Eastern Mediterranean
Transmission : definitive host : liver of Ovis aries, Capra hircus, Bos taurus; first intermediate host : Helicella obvia ; infection is acquired by accidentally eating the second intermediate host (17 species of Formica spp. and Lasius spp.) with raw fruits, vegetables, herbs or even with the drinking water
=> dicrocoeliasis / dicrocoeliosis / lancet fluke disease : hepatobiliary distomatosis
• Dicrocoelium hospes : a species found in the gallbladder of cattle in the Sudan
• Dicrocoelium macrostomum : a species found in the gallbladder of guinea fowl in Egypt
• Eurytrema
• Eurytrema coelomaticum and Eurytrema pancreaticum are found in the pancreatic ducts of sheep and cattle; humans occasionally become infected by eating inadequately cooked livers of other animals
• Platynosomum
• Platynosomum fastosum infests the liver and bile ducts of domestic Felis catus in the southeastern United States and the Caribbean after they eat infested lizards or toads
• Troglotremata : a family of trematodes that includes the genera
• Paragonimidae (lung-dwelling flukes)
• Paragonimus
• Paragonimus africanus : a species that parasitizes humans and carnivores.
Epidemiology : Congo and Cameroon
• Paragonimus heterotremus
Epidemiology : China.
• Paragonimus hueitugensis
Epidemiology : China.
• Paragonimus iloktsuenensis

Epidemiology : Vietnam, Thailand, and China
• Paragonimus kellicotti : a species closely allied to P. westermani
Epidemiology : in the USA (2 autochthonous cases were described in Georgia and Missouri)
Transmission : found in Canis familiaris, Felis catus, and hogs. Pomatiopsis cincinnatiensis and Pomatiopsis lapidaria are intermediate hosts
• Paragonimus mexicanus

Epidemiology : Ecuador and Peru
• Paragonimus miyazakii

Epidemiology : Japan
• Paragonimus skrjabini

Epidemiology : China
• Paragonimus uterobilateralis
Epidemiology : Cameroon
• Paragonimus westermani (a.k.a. Paragonimus ringeri, Distoma westermani, Distoma ringeri, and Distoma pulmonale) : the lung fluke; it is oval or pear-shaped, pink to reddish brown in color, and found in cysts in the lungs and sometimes in the pleura, liver, abdominal cavity, and elsewhere. It causes parasitic hemoptysis in humans and other animals
Epidemiology : endemic in China, Korea, Japan, Taiwan, and the Philippines and has been detected in other countries including India
Transmission : ingestion of infected freshwater crabs or crayfish
Transmission : ingestion of incompletely cooked or pickled shellfish. The life cycle of this trematode includes 2 intermediate hosts. The first are snails, such as Semisulcospira, and the second are crabs and crayfishes, where the infective stage of the parasite (the metacercariae) are encysted. When Paragonimus eggs hatch in fresh water, the miracidium enters different snails and develops into cercaria, which infect freshwater crabs and crayfish, where they form cysts in gills and muscles. The major intermediate hosts which can transmit the infection to humans are crabs of the genera Eriocheir, Potamon and Sundathelphusa and crayfishes of the genus Cambaroides. If cooking of these is proper before eating there is no chance of infection being transmitted. Generally, in the endemic countries, crabs etc. are eaten either raw, in alcohol, or undercooked and this then can easily transmit the infection to humans.
Pathogenesis : after the ingestion of the cysts (metacercariae), they excyst in the stomach and the larvae come out, penetrate the gut wall, and migrate through the mesentery and diaphragm to reach the lungs, where they mature into the adult worms and after fertilization start to lay eggs. This normally takes about 3 months. The worms can lead to pulmonary paragonimiasis or can also reach aberrant sites and can cause cerebral, cutaneous paragonimiasis
=> paragonimiasis / paragonimosis / pulmonary distomiasis / lung fluke disease
• acute paragonimiasis : fever, cough, bronchitis, bronchiectasis, and tuberculoid symptoms, pleural effusion, hepatomegaly and splenomegaly
• chronic paragonimiasis (more common) is characterized by cough, dyspnea, parasitic hemoptysis (brown-flecked sputum), and pleuritic chest pain. X-ray shows (depending on length of illness) diffuse or segmented infiltrates, nodules, cavities, ring cysts, and/or pleural effusions. Extrapulmonary infections may manifest with abdominal pain, diarrhea, and CNS symptoms.
Laboratory examinations :
• detection of typical ova in blood-stained sputum. These can be detected only after adult worms are mature -- that is, 3 months after infection. Paragonimus is, therefore, an important differential diagnosis to tuberculosis. In the migratory phase, elevated eosinophils and IgE are common.
• detection of ova in stool in children.
• detection of antibody: ELISA test has been developed^{ref1, ref2, ref3, ref4} and the one developed by the CDC gives almost 96% sensitivity. The test uses 8 kda antigen of the worm.
• detection of antigen: This is better than antibody detection and gives 100% sensitivity. This should also be positive earlier than antibody detection, which takes at least 2 weeks to become positive.
• skin test: more of an epidemiological tool
Therefore:
• for an asymptomatic person it would be better to go for serology, as this would be positive well before the worms mature and lay eggs.
• if initial serology is negative it can be repeated after 10-14 days.
• if serology is positive in a non-endemic area, take it to be probable infection and it would be advisable to follow up and treat.
• regarding the moderator's previous query, I have no knowledge regarding cases after flash-fried crabs, but it would be possible, as temperature inside the muscle tissue of the crab may not reach the level necessary to kill the metacercariae.
• earlier treatment should prevent scarring and sequelae.
Treatment is with praziquantel 25 mg/kg tid for 2 days.
• Nanophyetus (a.k.a. Troglotrema)
• Nanophyetus salmincola (a.k.a. Troglotrema salmincola)
Epidemiology : sporadic cases are encountered in the Pacific Northwest coastal region. This is the most common systemic trematode in North America; lower Amur River valley (prevalence = 4.2%)^ref
Transmission : found in the kidney and under the skin of various fish, especially salmon and trout, and serves as a vector of Neorickettsia helminthoeca, the etiologic agent of salmon poisoning. It is transmitted to humans, dogs, Felis catus, foxes, bears, hogs, and other animals by the ingestion of raw infected salmonid fish (incompletely cooked or home-smoked salmon or steelhead trout) or by handling naturally highly infected coho salmon (Oncorhynchus kisutch)^ref.
=> nanophyetiasis : chronic enterocolitis : chronic diarrhea, nausea, abdominal discomfort
Laboratory examinations : eosinophilia (up to 43%), characteristic bipolar eggs in a stool specimen
Therapy : 10 mg/kg of praziquantel
• Strigeidida
• Schistosomatoidea
• Schistosomatidae (blood-dwelling flukes)
• Gigantobilharzia
• Heterobilharzia : a genus of trematodes of the family Schistosomatidae that parasitize mammals
• Heterobilharzia americana has cercariae that cause a nonpatent visceral schistosomiasis in humans.
• Schistosoma
Epidemiology : chronically infect 200 million individuals in 76 countries, mainly in tropical and subtropical areas; 120 million display symptoms, while another 600 million people are at risk of infection. Schistosomiasis is endemic in
• China : it is believed that 2.4 millions Chinese are infected with the disease, but, given the current prevalence of the carrier snail, a total of 65 million Chinese are in danger of being infected. In 2003 alone, 843 000 Chinese were infected, most of them living in frequently flooded areas along the Yangtze River, where the carrier snail has an ideal habitat. By the 1980s, China thought that it had effectively controlled snail fever, but a mixture of natural disasters, and human error, has facilitated its return. After a massive deluge along the Yangtze 6 years ago, the disease moved on to large, previously unaffected areas. The disease has been allowed to spread due to public ignorance and the erosion of China's healthcare system. An increase in schistosomiasis in China was reported in 2003 : < 1000 cases of Katayama fever were reported in the year 2000 -- the last year from which we have data -- as compared to > 12 000 cases in 1989. Hunan makes up almost 1/4th, or 210 000, of China's total infections. The disease also plagues Hubei, Jiangxi, Anhui, Jiangsu, Sichuan and Yunnan provinces.
• Ghana. Many rural health clinics lack praziquantel and are overburdened and ill-equipped to respond to an outbreak of the disease. Treatment is not available free of charge, and schistosomiasis control depends on control of the water snails -- the intermediate host -- and treatment of human cases to prevent excretion of Schistosoma eggs into the environment. Schistosomiasis has emerged as a big problem since the construction of the Volta River dam in 1964, as was also the case after construction of the Aswan dam in Egypt. The Volta dam's cost was estimated to break even in 57 years. It would be interesting to see how much the dam has cost the country's health system over time
Life cycle : schistosomulum : a stage in the life cycle of a schistosome occurring just after it has penetrated human skin as a cercaria; it loses its tail and becomes physiologically modified in order to be capable of anaerobic metabolism in the bloodstream
Genomics : estimated 15,000 genes
• Schistosoma bovis : a species found in the portal system of sheep and cattle in Iraq, Africa, and certain islands in the Mediterranean
• Schistosoma haematobium (a.k.a. Bilharzia haematobia and, formerly, Distoma haematobium and Distoma capense)
Epidemiology : a common parasite in North Africa, other parts of the Mediterranean littoral, and the Arabian peninsula
• Zimbabwe : endemic. A recent study from Zimbabwe^ref showed that 60% of women aged < 20 years are infected with the organism causing schistosomiasis. Another study from Zimbabwe found the same prevalence in schoolchildren^ref
Transmission : the parasites enter the body through the skin of persons coming in contact with infested waters, the invertebrate hosts being small snails of the genus Bulinus, including the subgenus Physopsis : Bulinus bavayi, Bulinus globosus, Bulinus liratus, Bulinus nyassanus,Bulinus obtusispira, Bulinus senegalensis, Bulinus truncatus, Bulinus umbilicatus, Bulinus wrighti, Ferrissia burnipi
=> the adult worms are found in the veins, especially those of the vesical plexus : urinary schistosomiasis / vesical schistosomiasis / endemic hematuria / genitourinary schistosomiasis / schistosomiasis haematobia (known ion Zanzibar as kichocho) : infection of the bladder. DTH due to soluble egg antigens (SEA) => cystitis => irritability of the bladder, hematuria, polyps => sclerosis => ureteral stenosis, hydroureter, hydronephrosis, pyelonephritis, acute renal failure. Complications: prostatitiscystospermitis, female genital schistosomiasis (FGS : cervicitis, endometritis<